The Ravens want to make their bird baths a little safer. The greatest swimmer of all time is here to help. Michael Phelps agreed to help Baltimore's players learn how to swim after an Instagram appeal from star cornerback Marlon Humphrey and some teammates: A post shared by Marlon Humphrey (@marlon) "Hey Mr.

Michael Phelps, the most decorated Olympian of all time, certainly knows a thing or two about swimming techniques.

Marlon Humphrey and other Ravens want to learn how to swim. Luckily for them, they landed the best teacher available: Michael Phelps.